The use of modems has increased dramatically in the past few years. A typical modem acts as a modulator/demodulator that modulates/demodulates at least one carrier signal to enable digital data to be carried over the analog telephone network. In a standard data telephony application, an analog carrier signal is modulated at a source modem to code digital information, and the modulated carrier signal is then sent over the analog telephone network to a destination modem that demodulates the analog carrier signal to extract the digital data. The connection between the modems is created by placing a telephone call from the source modem to the destination modem. One of the limitations of such data modem calls is that they cannot be readily transferred without the calls being dropped. With conventional voice telephone calls, the call may readily be transferred from one phone to another. However, attempting to transfer a data modem call from one data modem to another results in the call being dropped due to the interruption of the carrier signal. Data modems include built-in features for dropping a call if the carrier signal is interrupted for more than a negligible amount of time.
One environment in which this inability to transfer data modem calls has proven problematic is in Telecommunications Relay Service (TRS) centers. TRS centers are call centers that allow a hearing-impaired person to communicate over telephone lines using a workstation (such as a personal computer) and a modem to communicate with an operator at the TRS center. The operator at the TRS center communicates to the hearing-impaired person via a separate workstation and modem. In addition, the operator at the TRS center communicates with a person who is not earing-impaired via a conventional telephone set. The role of the TRS operator is to translate messages between the modem call with the hearing-impaired person and the voice call with the person who is not hearing impaired.
FIG. 1 shows an example of a typical configuration for a TRS center. The hearing-impaired party 10 communicates with the TRS center 12 in order to communicate with a nonhearing-impaired party 14. The hearing-impaired party has a workstation 22 that is interfaced with a data modem 20. A modem call is established between the modem 20 of the hearing-impaired party 10 and a data modem 30 at an operator station 24 within the TRS center 12. Data 16 is passed between the respective modems 20 and 30 as the modem call progresses. Messages from the hearing-impaired party 10 appear at a display device that is part of the workstation 32 of an operator at the operator station 24. The operator at operator station 24 also has a phone set 34 that is used to place a voice call with the nonhearing-impaired party 14. The nonhearing-impaired party 14 has a conventional telephone 28, and voice signals are transmitted between the nonhearing-impaired party 14 and the operator at the operator station 24.
A difficulty arises at the TRS center 12 when a new operator is required. For example, if the hearing-impaired party 10 or the nonhearing-impaired party 14 communicates in a natural language other than that understood by the operator, a new operator may be required. In conventional systems, this difficulty is handled by having a new operator physically take control of the operator station that is fielding the call. For the example depicted in FIG. 1, the operator at operator station 26 may be required to physically take over the operator station 24 in such a situation. This need for an operator to physically move to a new station is both cumbersome and inefficient. Moreover, this approach may be bothersome to the parties involved in the call because it may take a substantial amount of time.